Seasonal course of translocation, storage and remobilization of 13 C pulse‐labeled photoassimilate in naturally growing Larix gmelinii saplings

Summary•  Autocorrelation – correlation of tree‐ring parameters such as ring width, density and isotope ratios to the environmental conditions of the previous year(s) – is associated with the use of previous photoassimilate for current year's tree ring formation. •  To clarify the seasonal course of carbon allocation patterns among needles, branches, stem and roots, we pulse‐labeled 10 Larix gmelinii growing in a continuous permafrost zone with 13 CO 2 . •  Photoassimilate incorporated in June was allocated mainly to above‐ground parts, indicating active above‐ground growth in spring. Very little was allocated to below‐ground parts (2.6–7.9%), probably because root growth is inhibited by low soil temperatures in spring. Conversely, a higher proportion of July and August photoassimilate was allocated to below‐ground parts (32–44 and 12–24%, respectively). •  About half the carbon in new needles was derived from stored material. The starch pool in non‐needle parts, which can be used for xylem formation, drew approx. 43% of its carbon from the previous year's photoassimilate, indicating that carbon storage is a key mechanism behind autocorrelation in (isotope) dendroclimatology.